Baking with the low level bake API

This section describes the low level baking API (the EnlightenBake library).

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The initial stage of the baking is:

1. Decide which Enlighten IPrecompInputGeometry instances you want in each bake system. Each bake system represents one output lightmap.

2. Create an IBakeInputSystem for each bake system you want. Ensure the name is unique.

3. Set the resolution of the system in the Enlighten IBakeInputProperties, and if you are not creating your own lightmap UV stream, turn packing on here also. Use IBakeInputSystem::SetBakeProperties to pass the properties to the bake system.

4. For each instance in that system, create a Enlighten BakeInputMeshInfo object filling out the fields appropriately, and then call IBakeInputSystem::AddMesh().

5. Call IBakeInputSystem::Finalise(), and extract the new lightmap UV stream if packing was required.

Outputs from a previous stage are never modified by a later one, so you can often run these stages in parallel (for example, through distributed build systems such as IncrediBuild).

The diagram below shows the creation of one IBakeInputSystem. Repeat for each output map required.

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1. First, all the bake systems have to be combined into a BakeSystemResource object. This object is used to create a KD tree for the other stages to trace against, so requires updating if any geometry changes.

2. Next, copy lighting information into an IBakeInputLighting object.

3. Now, for each BakeSystemResource, create an IBakeVisibilityBuffer with the IBake API. This operation is slow; therefore if only the lights have changed (and not the geometry) you can pass in an IBakeVisibilityBuffer from a previous run and it will be updated.

4. Call IBake::BakeSystemDirect() to create the IBakeOutputSystemDirect. Optionally pass in a BakeSystemResource object to be able to apply a visibility-aware post-processing filter, with its size set as the filter size baking property. The final output texture, in FP16 format, can be pulled from this object.

The diagrams below show a scene with two IBakeInputSystems; there may be more or fewer than this.

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1. Create an IBakeInputRuntime and fill it with the RadSystemCore and InputWorkspace of each Enlighten system.

2. For each Enlighten system, create an IBakeInputSystem using all the Radiosity objects of the Enlighten system. This is required later in the process in order to fit the Enlighten lit instances to the bake system instances. Set the resolution of the IBakeInputSystem to the resolution of the Enlighten lightmap via an IBakeInputProperties object passed to the IBakeInputSystem::SetBakeProperties method.

3. For each Enlighten system, call IBake::CreateRuntimeLighting to create an IBakeRuntimeLighting from:

   1. the IBakeInputSystem that you just made

   2. the IPrecompSystemDuster

   3. the IPrecompPackedSystem

   4. the global IBakeInputLighting

4. For each runtime lighting you made:

   1. For each bake system representing the output lightmaps:

      1. Call IBake::UpdateRuntimeLighting to apply the light and albedo information for each bake system to the Enlighten system.

   2. Call IBake::FinaliseRuntimeLighting

5. Call IBake::RunEnlightenSolver; this takes all the information and spins a small Enlighten Runtime until the lighting values settle. This is run only once as it contains information about every system in the bake.

6. For each bake system, call IBake::BakeSystemIndirect and extract the indirect lighting from the IBakeOutputSystemIndirect it creates. Optionally pass in a BakeSystemResource object and a IBakeInputRayOriginPositions to be able to enable visibility-aware upsampling with the identically named baking property.

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Final Gather creates a refined version of the indirect lightmap through ray tracing, by using previously calculated indirect and direct lightmaps. The final gather baking thus has a dependency on all the IBakeOutputSystemIndirect and all the IBakeOutputSystemDirect objects previously created for the baked scene, as well as their matching IBakeInputSystem objects. It also has a dependency on the IBakeSystemResource object (used for raytracing) and the IBakeSolvedRuntime objects for the baked scene.

1. For each IBakeInputSystem, call IBake::BakeSystemFinalGather.

2. Extract the FP16 output textures from the resulting IBakeOutputSystemFinalGather objects.

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1. For each BakeSystemResource, call IBake::BakeSystemAO.

2. Extract the FP16 output textures from the resulting IBakeOutputSystemAO objects.

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1. First, copy lighting information into an IBakeInputLighting object.

2. Now, for each probe set represented by an IPrecompInputProbeSet, create an IBakeVisibilityBuffer with the IBake API. You also need to pass in a BakeSystemResource object, with all the systems that can influence the direct lighting for the probes. This operation is slow; therefore if only the lights have changed (and not the geometry) you can pass in an IBakeVisibilityBuffer from a previous run and it will be updated.

3. Call IBake::BakeProbeSetDirect() to create the IBakeOutputProbeSet. Use the IBakeOutputProbeSet::GetOutput() method to retrieve the SH coefficients of all probes in the probe set.

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1. First follow the steps described in Indirect light baking.

2. Now, for each probe in a probe set, use the IBakeSolvedRuntime::GetSolvedProbe() method of IBakeSolvedRuntime to retrieve the SH coefficients.

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The baked radiosity normal texture is needed when using baked directional irradiance to better bring out features when the fine-grained shading normal used in runtime deviates from the cruder normal used for computing radiosity. (typical example is re-lighting normal maps)

1. For each BakeInputSystem, call IBake::BakeSystemRadiosityNormal, providing the BakeSolvedRuntime for all Enlighten systems.

2. Extract the FP16 output textures from the resulting IBakeOutputSystemRadiosityNormal objects.

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If you experience problems when using the Low Level Precompute API, call the GeoAttachSystemLoggers/GeoAttachLogger functions to issue error and warning messages. For more information, see the API documentation at module Message Reporting and Error Handling.